A vehicle may include a common operation switch that controls multiple in-vehicle devices in a unified manner and reduces the number of operation switches that would be operated by a user. Specifically, a simple operation switch may allow the user to select and search through a hierarchy of command menus for each of the in-vehicle devices available through an interface displayed on a screen. Such a common operation switch is disclosed in, for example, Japanese Patent Laid-Open No. 2007-8246 (JP '246).
For instance, a top menu in the hierarchy would allow the user to select one operation target device from among the in-vehicle devices available, such as a navigation device, an audio system, a television, a radio, and an air-conditioner. After selecting, for example, a television in such menu, a television menu would appear to allow the user to input a TV operation, such as a volume control and a channel selection. After selecting a channel selection, a bottom menu in the hierarchy would appear, allowing the user to select a desired channel. The user would then select a desired channel (i.e., a desired command), which is displayed in a menu on the screen.
In such a case, an input operation performed by the user (e.g., a driver of the vehicle) via the operation switch may be very simple for enabling the driver to perform a quick selection of one option from among many options or commands. By providing the quick selection, the driver is able to operate the in-vehicle device while driving the vehicle.
However, simply providing many options and choices for the disposal of the user may not assist in quick selection. In other words, a menu with too many options may distract the driver from driving the vehicle for a prolonged period of time by requiring too many switch operations.